1. QSO absorption spectra and  -variation Group meeting 2 July 2007 Ruth Buning, Wim Ubachs, Michael Murphy, Lex Kaper, Huib Henrichs, Piet Mulders

2. Has changed on a cosmological timescale?

3. Empirical search for a change in  Compare H 2 spectra of different epochs: Compare H 2 spectra of different epochs: QSO 12 Gyr ago Lab today 90-112 nm x (1+z)

4.  /  and spectrum H 2 Recent finding, based on 76 lines in 2 QSO absorbers: Recent finding, based on 76 lines in 2 QSO absorbers: Accurately calculated Lab: 5 x 10 -8 QSO: (2-10) x 10 -7 4σ4σ

7. The QSO absorption sample >2300 HI absorption systems >2300 HI absorption systems ~600 DLA’s ~600 DLA’s 14 H 2 absorption systems (~15%) 14 H 2 absorption systems (~15%) 6 useful 6 useful 3 high-quality spectra 3 high-quality spectra Q0405: 37 lines at z abs =2.59 Q0405: 37 lines at z abs =2.59 Q0347: 39 lines at z abs =3.02 Q0347: 39 lines at z abs =3.02 J2123: ~50 lines at z abs =2.06 J2123: ~50 lines at z abs =2.06 1 next august 1 next august Q2348: ~20 lines at z abs =2.43 Q2348: ~20 lines at z abs =2.43

8. Aug. ’07 observations: The Instrument

9. Kueyen

10. Aug. ’07 observations: The Instrument

11. UVES: Ultraviolet – Visual Echelle Spectrograph

12. 300-500 nm 420-1100 nm

13. Spectrum quality Resolving power R=  Resolving power R=  –slitwidth SNR SNR –brightness/sky background –seeing –airmass –total exposure time

14. Aug. ’07 observations: Object data

16. Blue CCD chip Red CCD chip 1Red CCD chip 2 Lyman-  of quasar emission z emis =3.0236 C IV emission DLA at z abs =2.426 H 2 region z abs =2.426 DLA at z abs =2.615

17. Blue CCD chip Red CCD chip 1Red CCD chip 2 Lyman-  of quasar emission z emis =3.0236 C IV emission DLA at z abs =2.615 H 2 region z abs =2.426 DLA at z abs =2.93 DLA at z abs =2.426

18. Spectrum Q2348 DLA at z abs =2.426 Strong Ly  H 2 region Ly  at z abs =2.615 Lyman limit  at z abs =2.615

19. Spectrum Q2348 DLA at z abs =2.615 DLA at z abs =2.426 H 2 region Ly  at z abs =2.615 Lyman limit  at z abs =2.93

20. Data: H 2 absorption L0R0 line of H 2 > 7 velocity components

21. Aug. ’07 observations: Spectrum quality Now: Now: –Total exposure time 4.5 hr –R = 47,000 –SNR = 15 August: August: –Total exposure time 22 hr –R = 55,000 –SNR = >35

22. J2123 spectrum (Keck/HIRES, Prochaska) H 2 region Resolution 110,000 ; z abs =2.0593

23. J2123 spectrum H2H2 Ly 

24. Spectrum analysis Voigt profile Voigt profile Input: Input: – i 0 –K i –Oscillator strengths Fit parameters: Fit parameters: –Column density –Doppler parameter –z abs –  Also fit blended Ly  forest lines Also fit blended Ly  forest lines

25. Summary: QSO data for  /  determination Q0347: 37 lines Q0347: 37 lines Q0405: 39 lines Q0405: 39 lines Q2348: ~20 lines -> Aug. ‘07 Q2348: ~20 lines -> Aug. ‘07 J2123: ~50 lines -> to be analyzed J2123: ~50 lines -> to be analyzed

29. The QSO absorption sample Q 0515-441z=1.15 Q 1331+170z=1.78 Q 0551-336z=1.96 Q 0013-004z=1.97 Q 1444+014z=2.09 Q 1232+082z=2.34 Q 0841+129z=2.37 Q 2343+125z=2.43 Q 2348-011z=2.43 Q 0405-443z=2.59 Q 0528-250z=2.81 Q 0347-383z=3.02 Q 0000-263z=3.39 Q 1443+272z=4.22 …… Q 0515-441z=1.15 Q 1331+170z=1.78 Q 0551-336z=1.96 Q 0013-004z=1.97 J2123 z=2.06 Q 1444+014z=2.09 Q 1232+082z=2.34 Q 0841+129z=2.37 Q 2343+125z=2.43 Q 2348-011z=2.43 Q 0405-443z=2.59 Q 0528-250z=2.81 Q 0347-383z=3.02 Q 0000-263z=3.39 Q 1443+272z=4.22 …… H 2 very weak/tentative Too low z

30. Energy levels in a diatomic molecule Electronic Electronic Vibrationalv Vibrationalv RotationalJ RotationalJ

31. Representation of the energy levels Rotation: Rotation: Vibration: Vibration: (Rigid rotor) (Nonrigid rotor) (Harmonic oscillator) (Anharmonic oscillator)

32. Dunham representation Energies derived from Schrödinger equation and general potential function Energies derived from Schrödinger equation and general potential function These contain the parameters  e and B e, which are mass-dependent These contain the parameters  e and B e, which are mass-dependent

33. The sensitivity coefficients Dependence of transition wavelengths (or energies) on  quantified by sensitivity coefficients: Dependence of transition wavelengths (or energies) on  quantified by sensitivity coefficients: E and dE/dµ derived from Dunham expansion: E and dE/dµ derived from Dunham expansion:

34. The H 2 data Available lab data: Available lab data: –Lyman (B-X): v’=0-18, v’’=0 –Werner (C-X): v’=0-4, v’’=0 –J between 0 and 5